The present invention relates to the field of “medical devices” as may be defined, for example, by the Jun. 14, 1993 directive 93/42/CE of the European Communities. The present invention may also relate to the “active implantable medical devices” field as defined, for example, by the Jun. 20, 1990 directive 90/385/CEE of the European Communities.
Some implantable medical devices continuously monitor a patient's cardiac rhythm and, if necessary (e.g., in case of a rhythm disorder detected by the device), deliver electrical pulses to the heart for cardiac stimulation, resynchronization, cardioversion and/or defibrillation. Other implantable medical devices include neurological devices, cochlear implants, etc., as well as devices for pH measurement or devices for intracorporeal impedance measurement (such as the measure of the transpulmonary impedance or of the intracardiac impedance).
The invention relates even more particularly to those devices that implement autonomous implanted capsules which are free from any physical connection to a main implanted device (for example, main stimulation pulse generator).
These autonomous capsules are sometimes called “leadless capsules” to distinguish them from the electrodes or sensors placed at the distal end of a lead (e.g., a lead traversed throughout its length by one or more conductors galvanically connecting an electrode or a sensor to a generator).
Implants without leads (e.g., leadless capsules) are, as an example, described in U.S. 2007/0088397 A1 and WO 2007/047681 A2 (Nanostim, Inc.) or in U.S. 2006/0136004 A1 (EBR Systems, Inc.).
It is challenging and difficult to develop leadless capsules which have a long lifespan and yet remain very small and highly reliable (e.g., mechanically, electronically, bio-compatibly).